title: Menstrual- and gender-dependent variations in circulating IL-1 agonists, antagonists, and binding proteins.
abstract: This study tested the hypotheses that sex-related differences in circulating binding proteins for interleukin- 1beta (IL- 1beta ) exist and that these binding proteins affect immunoassays for IL-1beta and IL-1Ra. 125I-labeled IL-1beta was added to human plasma samples, then chromatographed. The percentages of total radioactivity eluting in a high-molecular-weight peak were 21.0 + 0.8 for men (n = 6), 19.1+/-0.9 for follicular phase women (n = 6), and 18.0+/-0.8 in luteal phase women (n = 6; men vs. women, P = 0.032; follicular vs. luteal, P = 0.035), and correlated with plasma sIL-1RII concentrations (r = 0.647, P = 0.007). Plasma IL-1beta immunoreactivity did not correspond to concurrent cellular secretion rates due, in part, to interference in the IL-1beta assay by sIL-1RII. Correspondence between plasma IL-1Ra levels and cellular secretion rates was observed only after serial dilutions of the samples. These results indicate that plasma IL-1beta binding capacity differs between men and women and that sIL-1RII is a major contributing factor. Furthermore, relating plasma IL-1 isoform immunoreactivity to functional measures (tracer binding) or concurrent release by isolated cells can lead to insights about assay interferences that may exist in plasma.
authors.affiliation: New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts, USA. jgc2@psu.edu
authors.forename: J G
authors.initials: JG
authors.lastname: Cannon
authors.forename: L W
authors.initials: LW
authors.lastname: Abad
authors.forename: E
authors.initials: E
authors.lastname: Vannier
authors.forename: E A
authors.initials: EA
authors.lastname: Lynch
mesh_terms: D001798:Blood Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000097:blood*; D008297:Male; D008598:Menstruation; D011485:Protein Binding; D017472:Receptors, Interleukin-1 / Q000378:metabolism; D012795:Sialoglycoproteins / Q000378:metabolism; D012995:Solubility; D000511:alpha-Macroglobulins / Q000378:metabolism
chemical_list: D001798:Blood Proteins; C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D017472:Receptors, Interleukin-1; D012795:Sialoglycoproteins; D000511:alpha-Macroglobulins